This proposal has focused on development of several reproducible techniques for measuring immune complexes and application of these approaches to common clinical conditions as well as unique types of infectious disease processes. Infections where specific antigens can be recognized utilizing immunospecific identification of the antigen-part of detectable complexes have been studied--including leprosy, shigellosis, acute rheumatic fever, disseminated gonococcal infection and most recetly Lyme arthritis. Additional studies have focused on mechanisms involved in generation or potentiation of relative immune deficiency. These studies have included a search for suppressor cell activity in human cord blood lymphocytes as well as studies of human cell surface markers possibly associated with suppressor cell activity.